Re: [ft-devel] completed CPAL/COLR support

[Behdad Esfahbod]

I haven't got time to fully review the API. But just taking a look now, in the example in freetype.h:
   *     if ( palette && layer_glyph_index )
   *     {
   *       do
   *       {
   *         FT_Color  layer_color = palette[layer_color_index];
   *
   *
   *         // Load and render glyph `layer_glyph_index', then
   *         // blend resulting pixmap with previously created pixmaps.
   *
   *       } while ( ( layer_glyph_index =
   *                     FT_Get_Color_Glyph_Layer( face,
   *                                               glyph_index,
   *                                               &layer_color_index,
   *                                               &iterator ) ) != 0 );
   *     }

First, I think the use of a FT_LayerIterator type is unnecessary. A single index could have done.

Second, the use of 0 return value to signify end of iteration is problematic given that 0 is a valid glyph index that can appear in the layers itself.

Third, "palette[layer_color_index]" is recipe for invalid memory access.  Let alone that it does not handle the foreground color magic number 0xFFFF.

b

On Sun, Jun 17, 2018 at 1:17 PM, Werner LEMBERG <address@hidden> wrote:

>> the CPAL/COLR interface is now implemented and committed to git.
>> However, it is still mainly untested; I'm working on it the next
>> days – be warned that there might be issues.
>
> If I combine FT_LOAD_COLOR and FT_LOAD_TARGET_LCD, should I get LCD
> optimized results with separate alpha used for each color channel?

I don't understand the question.  The BGRA format only supports a single
alpha for the three color channels...

> I would love to have FT_LOAD_COLOR_STRAIGHT for non-premultiplied
> output.

Do we really need that?  Using `FT_Get_Color_Glyph_Layer' in
combination with `FT_Palette_Select' you can easily extract the colors
and do the blending appropriate blending function outside of FreeType.


    Werner

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behdad
http://behdad.org/